Can't map to <C-Insert>

Question

I'm trying to use ac to copy the whole contents to the system clipboard in gVim. Putting this in my .vimrc isn't working:

nnoremap <leader>ac ggvG$<C-Insert>

If I manually press ggvG$[Ctrl-Insert] from normal mode, it works as expected: goes to the top, selects to the bottom, copies it all, and drops me in normal mode at the top of the file.

When I set nnoremap <leader>ac ggvG$<C-Insert> in my .vimrc, and then activate it (with [Space]ac), it selects from the top to the bottom, beeps an error, and then just sits there in visual mode with the whole file selected.
If I manually press [Ctrl-Insert] at that point, it finishes as expected. So I'm pretty sure vim's just not doing the <C-Insert> part.

I further tested by adding this vnoremap <leader>ci <C-Insert>.
I selected a word or a line in visual mode, activated that map, and got a beep and no copying. A manual [Ctrl-Insert] works fine.

So why can't I map to <C-Insert>?

Answer 1

help c-insert will tell you that "*y will do the same as <C-Insert>.

So try

nnoremap <leader>ac ggVG"*y

(using V as it makes more sense)

While I didn't check, Vim says it's a standard DOS mapping so

nmap <leader>ac ggVG<c-insert>

may work as well.